The classic E36 crank-sensor (M50/M52) failure is a heat-related crank-but-no-start: the engine cranks normally but won't fire, often once warmed up, and it can be intermittent — no crank signal means the DME fires no spark and no injection.
Test it by unplugging the connector and measuring across the two signal pins: it's an inductive sensor reading roughly 540 ohms (about 486-594).
Watch a common trap — some Bentley printings list
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